Controlled engine exhaust gas recirculation is a commonly used technique for reducing oxides of nitrogen in products of combustion that are exhausted from an internal combustion engine to atmosphere. A known EGR system comprises an EGR valve that is controlled by an electric circuit in accordance with various engine operating conditions to regulate the amount of engine exhaust gas that is recirculated to the induction fuel-air flow entering the engine for combustion so as to limit the combustion temperature and hence reduce the formation of oxides of nitrogen.
When an EGR valve is engine-mounted, it is exposed to a harsh operating environment that includes wide temperature extremes and vibrations. Exhaust emission requirements impose more stringent demands for improved control of such valves, and a valve that contains both an electric actuator for positioning the valve member and a position sensor for providing feedback of the valve member position to the control circuit may be capable of providing improved control. In order for such a valve to be commercially successful, its components must be able to perform properly in such extreme environments for an extended period of usage. Moreover, in mass-production automotive vehicle applications, component cost-effectiveness and size may be significant considerations. An EGR valve that possesses more accurate and quicker response can be advantageous by, providing improved control of tailpipe emissions, improved driveability, and/or improved fuel economy for a vehicle having an internal combustion engine that is equipped with an EGR system.
Size of an EGR valve may also be an important consideration in its commercial appeal. A valve that is more compact in size can be advantageous because of limitations on available space in a vehicle engine compartment and/or on a engine.